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Review and Outlook of Kaon Branching Ratios Measurements at KLOE

This review covers absolute branching ratio measurements and form factors of kaons, focusing on KLOE experiments at Frascati. It includes a search for direct CP-violation in K± decays, measurement of pp scattering, and more, providing insights into kaons and their decay processes with detailed data analysis and experimental outcomes.

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Review and Outlook of Kaon Branching Ratios Measurements at KLOE

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  1. Review KLOE (Frascati) Absolute Branching Ratios Kaon Lifetime Form-Factors NA48/2 (CERN) Search Direct CP-Violation in K± Measurement of pp scattering length RK=G(K+ e+n) /G(K+m+n) E391a (KEK) K0→p0nn KTeV (Fermilab) Radiative decays Outlook DANAE JPARC K0L→p0nn CERN-P-326 (NA48/3) K+→p+nn Review & Outlook, Kaons Augusto Ceccucci/CERN Vus FPCP -- Vancouver

  2. KLOE@DAFNE Frascati e+ e- f K+ K- (K0S K0L) • Advantages: • K0S and K0L tagging • Measure of absolute BR • Kaons have definite momentum • Study of K0S and K0L semileptonic decays without ambiguities • Low K momentum • K0L and K+ lifetimes measurements can be done precisely FPCP -- Vancouver

  3. × 102 Events/0.3 ns PK = 110 MeV 6 - 24.8 ns 40-165 cm 0.37 lL L/bgc (ns) KLOE K0L Measurements KL p0p0p0 hep-ex/0601038 K0L(e3) • Quadratic fit: 1 +l+t/mp+ + 1/2l+(t/mp+)2 • l+ = (25.5  1.5  1.0)  10-3 • l+ = ( 1.4  0.7  0.4)  10-3 • Correlation: r(l+, l+) = -0.95 • Pole model fit: MV = 870(7) MeV PLB626 (2005) 15 BR(K0L) =1  KL)= (50.72  0.14  0.33) ns BR(KL e() ) = 0.4007  0.0006stat 0.0014syst BR(KL () ) = 0.2698  0.0006stat 0.0014syst BR(KL 3) = 0.1997  0.0005stat 0.0019syst BR(KL () ) = 0.1263  0.0005stat 0.0011syst tL = 50.92  0.17  0.25 ns Vosburgh et al. ’72: tL = 51.54 ± 0.44 ns FPCP -- Vancouver PLB608(2005) 199

  4. |Vus|f+(0) Only KLOE provides BR,tL & f.f. (for IeK) Blucher & Marciano PDG 05 f+(0)=0.961+/-0.008 Leutwyler & Roos FPCP -- Vancouver

  5. NA48/2 (CERN-SPS) • 2003run: ~ 50 days • 2004run: ~ 60 days • Total statistics in 2 years: • K  + : ~4·109 • K 0 0 : ~2·108 • ~ 200 TB of data recorded Beam pipe • 400 GeV/c SPS protons • 60 GeV/c secondary hadron beams • Simultaneous collection • of K+ and K-decays FPCP -- Vancouver

  6. Direct CP-violation in K+/- p+/- p+p- K+/-p+/- p0p0 Lorentz-invariants u = (s3-s0)/m2; v = (s2-s1)/m2; si = (PK-Pi)2, i=1,2,3 (3=odd ); s0 = (s1+s2+s3)/3. |M(u,v)|2 ~ 1 + gu + hu2+ kv2 • Measured quantity sensitive to direct CP violation: Slope asymmetry: Ag = (g+-g-)/(g++g-)≠0 Centre of mass frame u = 2mK∙(mK/3-Eodd)/m2; v = 2mK∙(E1-E2)/m2. SM estimates vary within an order of magnitude (few 10-6…8x10-5). Models beyond SM predict substantial enhancement FPCP -- Vancouver

  7. Selected Statistics 2003 M=1.7 MeV/c2 Data-taking 2003: 1.61x109 events selected Events |V| even pion in beam pipe  K+ : 1.03x109 events odd pion in beam pipe  K: 0.58x109 events FPCP -- Vancouver U

  8. Jura (Left) A+ A- Salève (Right) Y X Achromats: K+ Up B+ Z B- Achromats: K+Down Stability and Systematics Control of Detector asymmetry Control of Beamline asymmetry FPCP -- Vancouver

  9. NA48/2 (2003 data) K+/-p+/- p+p- Slope difference: Δg = (-0.7±0.9stat.±0.6stat.(trig.)±0.6syst.)x10-4 = (-0.7±1.0)x10-4 Charge asymmetry: Ag = (1.7±2.1stat.±1.4stat.(trig.)±1.4syst.)x10-4 = (1.7±2.9)x10-4 K+/-p+/- p0p0 Slope difference: Δg = (2.3 ± 2.8stat. ± 1.3trig.(stat.) ± 1.0syst. ± 0.3ext.)x10-4 = (2.2 ± 3.1)x10-4 Charge asymmetry: [using g0=0.638 ] A0g = (1.8 ± 2.2stat. ± 1.0trig.(stat.) ± 0.8syst. ± 0.2ext.)x10-4 = (1.8 ± 2.6)x10-4 hep-ex/0602014; PLB 634 (2006) Order of magnitude improvement FPCP -- Vancouver

  10. Observation of p-p scattering effect in K→3p decays NA48/2 has made the first observation the of the charge exchange process+00in the K00decay. 1 bin = 0.00015 GeV2 30M events NA48/2 PLB 633 (2006) hep-ex/0511056 4mπ+2 K±±00 4mπ+2 G~|M0+M1|2 N. Cabibbo, hep-ph/0405001 PRL 93121801 (2004) N. Cabibbo and G. Isidori, hep-ph/0502130 JHEP 503 (2005) M2(00) (GeV/c 2)2 FPCP -- Vancouver

  11. Difference between p-p scattering length in I=0 and I=2 states NA48/2 PLB 633 (2006) hep-ex/0511056 (a0 – a2)m+ = 0.268 ± 0.010(stat) ± 0.004(syst) ± 0.013(theor) In agreement with theory (a0 – a2)m+ = 0.265 ± 0.004 (Colangelo 2001) FPCP -- Vancouver

  12. RK=G(K+ e+n) /G(K+m+n) NA48/2 EPS05 hep-ph/0511289 FPCP -- Vancouver

  13. CKM Unitarity and Rare Kaon Decays The unitarity of the CKM matrix can be expressed by triangles in a complex plane. There are six triangles but one is more “triangular”: VudVub*+VcdVcb*+VtdVtb*=0 Wolfenstein parameterization: Vus ~lVcb ~ l2 A Vub ~ l3 A(r- ih) Vtd ~ l3 A(1-r- ih) Sensitive to |Vtd| SM: BR(K+p+nn)  (1.6×10-5)|Vcb|4[sh2+(rc-r)2]  (8.0 ± 1.1)×10-11 BR(KLp0nn)  (7.6×10-5)|Vcb|4h2  (3.0 ± 0.6)×10-11 Im lt = A2l5h Re lt = A2l5r FPCP -- Vancouver

  14. Reminder: K+→p+nn hep-ex/0403036 PRL93 (2004) AGS Stopped K+ ~0.1 % acceptance BR(K+→ p+ nn ) = 1.47+1.30-0.89 × 10-10 FPCP -- Vancouver

  15. K0Lp0nn :E391a Upper Limit Mgg=Mp0 Require missing Pt • 10% of RUN I • Pencil beam • Expected background • from K0Ldecays: 0.02 • Acceptance: 0.73% • BR(K0Lp0nn)<2.8610-7 90%CL • Preliminary (KAON2005) • 6 improvement over KTeV one day special run • 2 improvement over published limit (KTeV Dalitz technique) FPCP -- Vancouver

  16. Kaon Radiative Decays (KTeV, preliminary) • K0Lp+p-g • gM1 = 1.198 +/- 0.035 (stat) +/- 0.086 (syst) • a1/a2 = -0.738 +/- 0.007 (stat) +/- 0.018 (syst) • gE1 < 0.21 (90% CL) • BR(K0Lp0p0g) < 2.52 10-7 90%CL • BR(K0Lpene+e-,Mee>5 MeV/c2) = 1.606 +/- 0.012(stat)+0.026-0.016(syst)+/-0.045(ext.) 10-5 • BR(p0 e+e-,X>0.95)=6.56+/-0.26(stat) +/- 0.23(syst) 10-8 • K0L e+e-g • BR(K0L e+e-g) = 9.25 +/- 0.03(stat) +/- 0.07(syst) +/- 0.26 (ext) 10-6 • CaK* = -0.517 +/- 0.030 (fit) +/- 0.022 (syst) • aDIP= -1.729 +/- 0.043(fit) +/- 0.028(syst) • BR(K0Lp+p-p0g) = 1.70 +/- 0.03(stat)+/- 0.04(syst)) +/- 0.03(norm) 10-4 • BR(K0Lp+p-p0e+e-,Eee>20 MeV/c2) = 1.60 +/- 0.18(stat) 10-7 FPCP -- Vancouver

  17. OUTLOOK FPCP -- Vancouver

  18. DAFNE Luminosity and plans • Last KLOE run: 2006 • DAFNE runs until 2008 for other experiments: FINUDA +SIDDHARTA • Plans for Luminosity and Energy upgrades (DANAE) • DANAE Motivation: • Kaon interferometry • Nuclear Physics • N N form factor • Synchrotron rad. • R&D FPCP -- Vancouver

  19. Outlook: K0Lp0nn • KOPIO @ BNL stopped • In Japan a step by step approach is followed: • KEK: • E391a has completed data taking (three runs) • They aim to reach the Grossman-Nir bound from the accumulated data • J-PARC • A proposal is being prepared for the new J-PARC hadron facility • Step I: move the E391a detector at J-PARC • Step II: build a new detector and a dedicated beamline to be able reach ~ 100 SM events FPCP -- Vancouver

  20. E391a Expected sensitivity KTeV Limit (Current Exp. Limit) Single Event Sensitivity From: T. Inagaki G-N Limit 1-day 1-week Run-I Run-II Run-III FPCP -- Vancouver

  21. Outlook: K0L→p0nn From Taku Yamanaka From Taku Yamanaka FPCP -- Vancouver

  22. CERN-SPSC-2005-013 SPSC-P-326 Proposal to Measure the Rare Decay K+p+ n n at the CERN SPS CERN, Dubna, Ferrara, Florence, Frascati, Mainz, Merced, Moscow, Naples, Perugia, Protvino, Pisa, Rome, Saclay, San Luis Potosi, Sofia, Turin FPCP -- Vancouver

  23. Setting the bar for the next generation of K+→p+nn experiments E787/E949: BR(K+→ p+ nn ) = 1.47+1.30-0.89 × 10-10 Current constraint on r,hplane ? 100 events Mean=SM 100 events Mean=E787/949 FPCP -- Vancouver

  24. P-326 Detector Layout K+p+ n n Gigatracker p+ K+ ~11 MHz n 75 GeV/c 800 MHz beam p/K/p n (KABES) FPCP -- Vancouver

  25. Background rejection 1) Kinematical Rejection 2) Photon vetoes and PID (p-m) Basic idea to reject K+ p+p0 : P(K+)= 75 GeV/c Require P(p+) < 35 GeV/c P(p0) > 40GeV/c It can be hardly missed in the calorimeters Region I: 0 < m2miss < 0.01 GeV2/c Region II: 0.026 < m2miss < 0.068 GeV2/c4 FPCP -- Vancouver

  26. qp PK Pp qK Gigatracker Provide very good time resolution Minimise mass (multiple scattering and beam interactions) Sustain high, non-uniform rate ( 800 MHz total) • Two Silicon micro-pixel detectors (SPIBES) • Timing • Pattern Recognition • Improved KABES (micromegas TPC) • To minimise scattering in the last station SPIBES: X/X0 << 1% Pixel size ~ 300 x 300 mm s(p)/p ~ 0.4% excellent time resolution to select the right kaon track Dependence of the signal to background (from K+p+p0) ratio as a function of the gigatracker time resolution FPCP -- Vancouver 26

  27. Photon E=11 GeV Pion P=42 GeV/c Cluster not reconstructed Eg = 22 GeV Expected position LKr inefficiency measured with data K+p+ p0 collected by NA48 in 2004 p+ track and lower energy g are use to predict the position of the other g LKr ineff. per photon (Eg > 10 GeV): h = (2.8 ± 1.1stat ± 2.3syst) × 10-5 (prel.) K+p+p0p0 FPCP -- Vancouver

  28. Signal & backgrounds from K decays / year* *Before taxes. Proposal quotes 40 evt/year @BR=10-10 • SPS used as LHC injector (so it will run in the future) • No flagrant time overlap with CNGS • P-326 fully compatible with the rest of CERN fixed target • because P-326 needs only ~1/20 of the SPS protons • Beam time estimates based on decennial NA48 experience at SPS FPCP -- Vancouver

  29. Status of P-326 (a.k.a. NA48/3) • Presented at the CERN SPSC in September 2005 • R&D endorsed by CERN Research Board on December 2005 • Beam Test foreseen in August 2006 • Seeking more groups to join • Aims to receive full approval by end of 2006…. • …to be able to start data taking some time in 2009-2010 FPCP -- Vancouver

  30. Conclusions • The last two years have been MIXED for kaon physics. On the one side there have been excellent results: • Vus Renaissence • Precise bounds on Direct CP-Violation in charged kaon decays • Progress on K0Lp0nn • Some surprises • BUT on the other side: • All US-based future programmes have been stopped !! Action is needed to keep KAONS at the heart of Flavour Physics & CP-Violation FPCP -- Vancouver

  31. SPARE SLIDES FPCP -- Vancouver

  32. y 2mm/bin x 2mm/bin Station 1(pixels) 2(pixels) 3(FTPC) Gigatracker (Hybrid Pixel) G. Anelli, M. Scarpa, S. Tiuraniemi • 200 mm Silicon sensor (>11 000 e/h mip) • Following Alice SPD • Bump-bonding • Read-out chip • Pixel 300 mm x 300 mm • Thinned down to ~100 mm (Alice SPD 150 mm) • Beam surface ~ 14 cm2 • Adapted to the size of the SPIBES r-o chips • ~125 mm Cfibre for cooling & support Front End and R/O considerations based on the experience of the CERN-PH/MIC and PH/ED Groups with the ALICE SPD FPCP -- Vancouver MeV

  33. Example: “hadronic” cluster of a photon Expected energy: ~29 GeV Deposited energy: ~9 GeV Maximum energy ~300 MeV Expected g position • Measured LKr inefficiency per photon (Eg > 10 GeV): • h = (2.8 ± 1.1stat ± 2.3syst) × 10-5 (preliminary) FPCP -- Vancouver

  34. Jura (Left) A+ A- Salève (Right) Y X Achromats: K+ Up B+ Z B- Achromats: K+Down Acceptance equalisation for K+ and K- Detector Left-Right asymmetry cancellation in the 4 K+/K­ ratios: ♦ ♦ ♦ ♦ Quadruple ratio: R(u) = RUS(u)RUJ(u)RDS(u)RDJ(u) = (1 + 4 Δg u) Cancellation of systematic biases: - DetectorL-Rasymmetries ( K+Salève/ K-Salève and K+Jura / K-Jura) - Beam line biases ( K+ beam Up / K- beam Up and K+ beam Down / K- beam Down) - Global time-variable biases (K+ and K- simultaneously recorded) Fit of R(u) is sensitive only to the time variation of asymmetries in experimental conditions with characteristic time smaller than corresponding field alternation periods (beam week, detector day)  2003 data taken in 4 SUPER-SAMPLES of 2 weeks each FPCP -- Vancouver

  35. RICH Layout FPCP -- Vancouver

  36. Downstream straw tracker • 6 chambers with 4 double layers of straw tubes each ( 9.6 mm) • Rate: ~45 KHz per tube (max 0.5 MHz) (m+p) 2.3 m Operate in high vacuum Low X/X0 z y 7.2 m X/X0 ~ 0.1% per view x 130 mm / hit s(P)/P = 0.23%  0.005%P s(q) ~ 50  20 mrad Good space resolution 7.2 m Redundant momentum measurement 2 magnets: 270 and 360 MeV Ptkick 5.4 m 8.8 m 5 cm radius beam holes displaced in the bending plane according to the 75 GeV/c beam path Veto for charged negative particles up to 60 GeV/c FPCP -- Vancouver

  37. P-326 Detector Layout K+p+p0 Gigatracker p+ g K+ ~11 MHz g 75 GeV/c 800 MHz beam p/K/p (KABES) FPCP -- Vancouver

  38. Energy of photons from K+ p+p0 hitting LKr: > 1 GeV GeV NA48 LKr as Photon Veto Consolidation of the safety/control system and read-out under way FPCP -- Vancouver

  39. Backgrounds not kinematically constrained They span accross the signal regions Must rely on Particle ID and veto 8% of K+ decays FPCP -- Vancouver

  40. New high-intensity K+ beam for P-326 Already Available FPCP -- Vancouver

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